The procedure for Example 1 in U.S. Pat. No. 5,525,668 DSM Copolymer Inc. uses an MAH grafted EP elastomer in combination with a ungrafted EP elastomer as an impact modifier in a polyamide blend prepared in a two-step process. The components are first blended in a Brabender mixer to initiate melting and secondly the curatives are added to vulcanize the elastomer. The compounding occurs in a batch reactor and requires a second mixing step for homogenization and a total residence time of 10-12 minutes. In example 5 the EP elastomer backbone prior to grafting contained 55 mol % of ethylene derived units and had a molecular weight as reflected in a Mooney viscosity (1+4) at 257° F. of 20 after grafting the polymer contained 1.7 wt % MAH. The options for the ungrafted EP elastomer included an EP-ENB terpolymer having a 65:35 molar ratio of ethylene to propylene and 8.5 wt % ENB and had a RSV of 2.3 in decalin. Another option was an ungrafted EP elastomer also included an EP copolymer having an RSV of 2.8 containing 55 mole % ethylene. Table V shows combination using 30 parts by weight of polyamide. The two step blending approach risks consumption of the curatives prior to their dispersion in the blend and the cross-linking action of the elastomer.
EP946642 describes the production of a flexible polyamide blend not relying on cross-linking. Certain viscosity limits are observed for the polymeric components to ensure dispersion of the majority rubber composition in a polyamide matrix. Thus the use of this technique limits the range of blends that can be made and properties that can be obtained.
U.S. Pat. No. 6,538,066 The Yokohama Rubber Co. Ltd discloses a thermoplastic elastomer composition obtained by blending a polyamide with brominated isobutylene-p-methyl styrene copolymer.
It is among the objects of the invention to provide modifiers for preparing improved thermoplastic alloys and especially polyamide alloys, which can be employed in a single step, dynamic vulcanization process, that may incorporate high levels of elastomer modifier while still providing a continuous matrix of a polyamide or other condensation polymers having functional groups. It is further among the objects of the invention to provide improved alloys with an improved balance of end use properties and in particular flexural modulus, tensile strength and oil aging suitable for example for automotive under the hood applications.
U.S. Pat. No. 5,783,629 describes a composition of a polyolefin which may be a polypropylene, an EPDM having a Mooney of from 10 to 120 and an amorphous low molecular weight polyolefin having a molecular weight of from 1000 to 15000 which may be an ethylene copolymer or a block copolymer. The composition does not contain a cross-linking component effective to provide cross-linking during subsequent melt blending.
JP200290441 describes a composition from a maleated EPDM, an ethylene- alpha-olefin copolymer and nylon. The composition does not include a non-maleated EPDM or a maleated interpolymer of ethylene and an alpha-olefin having from 4 to 12 carbon atoms.